micro unit 2 exam – Flashcards
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Unlock answers| What substances can damage the plasma membrane? |
alcohol detergent polymyxin antibiotics |
| Why is the plasma membrane a good target for antibiotics? |
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How do salty foods prevent the growth of bacteria?
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| Hypertonic environments, the cell shrinks and water moves out. |
| What antibiotic/substances can damage Gram-positive cells? |
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What antibiotic/substances can damage Gram-negative cells?
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| Which microscope can see internal structures of a cell and needs ultrathin sections so electrons can pass through the specimen? |
| Transmission Electron Microscope |
| What microscope enhances diffraction of the light that passes through a live specimen to see the internal structures of cells with out stain? |
| Phase-contrast microscope |
| What microscope is used to stuy surface features of a specimen? |
| Scanning electron Microscope |
| What microscope uses visible light to see a specimen against a bright background and uses stains to create contrast? |
| compound light microscope |
| What microscope uses UV light, flourescent stains and antibodies to ake a specimen glow, and allows rapid detection of pathogens in tissues? |
| Fluorescence microscope |
| What microscope has a special condenser that blocks most light to see the outline of a live specimen with out staining? |
| Darkfield microscope |
| What is the ability of lenses to distinguish two points? |
| refraction |
What is the composition and function of the plasma membrane for a prokaryote? Eucaryote? |
Prokaryote- composition: made of phospholipids and proteins function: permeability, makes ATP, Transportation Eukaryote- composition: Phospholipid bilayer, sterols Funtion: transportation |
What is the comopsition and function of the cell wall of a prokaryote? eukayote?
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Prokaryote- composition: peptidoglycan Function: protection
Eukaryote- no cell walls |
What is the funtion and composition of ribosomes in a eukaryote? prokaryote? |
Both: function: protein synthesis composition: protein |
What is the composition and function of chromosomes in a prokaryote? eukaryote? |
Prokaryote- composition: nucleic acids (DNA) 1 chromosome Function: storage of information
Eukaryote- composition: 46 DNA function: storage of information
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| In what ways do eukaryotes and prokaryotes preform cell division? |
Prokaryotes: binary fission
Eukaryotes: meiosis and mitosis |
What is the optimum temp for Mesophiles? psychrophiles? psychrotrophs? Thermophiles? hyperthermophiles?
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in order: 37 C 13 C 23 C 62 C 93 C |
| What is the danger zone for bacteria where some may produce toxins? |
| 15 C - 51 C |
| What do microbes need to make organic molecules ot form their cell structures? What are these organic molecules? |
Carbon
Carbohydrates, proteins, lipids, nucleic acids |
| What element do microbes need as a source of energy? |
| carbon |
| What element do microbes need to make proteins and nucleic acids besides carbon? |
| nitrogen |
| How do microbes aquire nitrogen? |
protein sources (food)
Nitrogen fixing bacteria can get nitrogen from the atmosphere |
| What important role does sulfur play in microbial growth? |
| its needed to make some amino acids and vitamins |
| What element do microbes need to make nucleic acids and the bilayer of plasma membranes. |
| phosphorus |
| What element(s) do microbes need to make cofactors of enzymes? |
| trace elements, mineral elements |
| What are organic growth factors? Give an example of some. |
essential organic compounds from the environment
eg. vitamins, amino acids, and bases of DNA and RNA |
| What pH do bacteria like? |
| neutral, 6.5 - 7.5 |
What pH do fungi like?
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| acidic 5-6 |
Nutrients prepared to grow microbes eg. nutrient agar |
| Culture Medium |
| Contains no living microbes |
| sterile |
| microbe introduced into a culture medium to initate growth |
| inoculum |
| microbes growing in/on a culture medium |
| culture |
| contains only one species or strain |
| pure culture |
| a visible mass of microbial cells that arose from a single cell, spore, or a group of attached cells |
| colony |
what does preserbing bacterial cultures for a long term do to bacteria? How long does this last?
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totaly stops metabolism
years |
| What does preserving bacterial cultures for a short term do to bacteria? How long does this last? |
slows down metabolism
3-4 months |
| name and define 2 long term ways to preserve bacterial cultures and the temperature they are stored at |
Deep-freezing - in liquid nitrogen -50 to -95 C
Lyophilization- freeze drying; dehydrate in a vacuume then freeze -54 to -72 C |
| Name 2 methods of obtaining a pure culture |
pour plate method streak plate method |
Which culture media has a chemical composition that varies slightly per batch and is routinely used to grow many kinds of bacteria? eg. nutrient agar |
| Complex media |
| which culture media are we using where the exact chemical composition is known? |
| chemically defined media |
Which culture media suppresses the growth of uneanted microbes and encourages he growth of the desired microbe? eg. Sabourand agar |
| selective media |
| Which culture media makes it easier to distinguish colonies of desired microbes? |
| differential media |
| which culture media encourages the growth of the desired microbe? |
| enrichment media |
| What is the time for a cell to divide and its population to double called? |
| generation time |
| Which phase of the bacterial growth curve is intense cellular activity and no cell division? |
| lag phase |
| Which phase of the bacterial growth curve used to determine generation time, is most effective to treat infections, and is under optimum conditions? |
| log phase |
| Which phase of the bacterial growth curve is slower growth and has new cells and dying cells? |
| stationary phase |
| which phase of the bacterial growth curve shows a logarithmic decline where dying cells exceed new cells formed? |
| Death phase |
| Name the 4 phases of the bacterial growth curve. |
lag phase log phase stationary phase death phase |
| Name the 4 direct methods of measuring microbial growth. |
plate count most probable number (mpn) direct microscope count filtration |
| Which method of measuring microbial growth is a common method for estimating the number of bacteria in a sample, uses colony forming units (CFU), and assumes that each bacterial cell grows in a single colony? |
| Plate count |
| What are the advantages and disadvantages of a plate count in measuring microbial growth? |
A: counts only the number of living viable cells
D: -need a lot of materials to preform serial dilutions of a sample -requires time for incubation |
| Which method of measuring microbial growth is a statistical estimation of a bacterial count and is used when microbes wont grow on solid media or will only grow in liquid differential media. |
| Most Probale Number (MPN) |
| which method in measuring microbial growth uses a special slide that can hold a measured volume of bacterial suspension? |
| direct microscope count |
| What are the advantages and disadvantages of the direct microscope count method in measuring microbial growth? |
A: a fast way of counting the number of cells D: -requires a high concenration of cells in a sample -does not work if the baceria are motile -counts living and dead cells |
| which method in measuring microbial gowth is where bacteria are sieved out onto the surface of a membrane filter then transferred to a culture medium and the CFUs are counted? |
| Filtration method |
| Which method in measuring microbial growth is a useful method when the bacterial count is low? |
| Filtration method |
| Name the 3 indirect methods of measuring microbial growth. |
turbidity metabolic activity dry weight |
| Which method for measuring microbial growth measures the level of cloudiness and uses an instrument that measures he amount of light that passes through a suspension of cells? What is that instrument called? |
Turbidity
spectrophotometer |
| Which method in measuring microbial growth measures he amount of metaolic profucts such as acid, gas, and enzyme production? |
| Metabolic Activity method |
| Which method in measuring microbial growth is used for filamentous organisms, like fungi and algae, that can be grown, dried, and weighed? |
| Dry weight method |
| What is the structure in a bacteria that is small, circular, self replicating DNA that may contain a few genes? |
| plasmid |
| What type of media is a Mannitol salt agar? |
| selective and differential |
| what type of medium is a blood agar? |
| differential |
